Portable laser frequency standard at 633 nm with compact external-cavity diode laser

摘要

A portable (32 cm×13 cm×6 cm) laser frequency standard has been constructed by frequency-stabilizing a miniaturized external-cavity diode laser to the Doppler-free spectrum of iodine. Compact structure is achieved using a novel transmission grating. The laser has excellent noise properties, which leads to a high signal-to-noise ratio (SNR) of detection and allows direct observation of the inverse Lamb dips. The frequency stability matches that of iodine-stabilized He-Ne lasers at 633 nm; the relative frequency stability (square root of the Allan variance) follows a slope of 7.9×10~(-12) τ~(-1/2) (10 s<τ<4000 s). The best stability, 1×10~(-13) (47 Hz), is reached at an integration time of τ=4000 s. The observed day-to-day repeatability (1σ) is 4×10~(-12) (1.6 kHz). Extensive measurements were made to evaluate the dependence of the laser frequency on the various operational parameters.